This is how the wrist and forearm act in the process of a Forehand

Here we see first a radial movement (1) of the wrist within the backswing phase (setting up the racquet), then in the further progression in the stroke phase a dorsal movement (2) (stretching of the wrist ) and an ulnar movement (3 – when lowering the racquet), as well as in the outswing phase a pronation (4) of the forearm, combined with a radial movement (5) at the end of the outswing.